Better test for #54.

test/transition/transition-test.js

@@ -0,0 +1,24 @@
+var tape = require("tape"),
+    jsdom = require("jsdom"),
+    d3_timer = require("d3-timer"),
+    d3_selection = require("d3-selection");
+
+require("../../");
+
+tape("transition.transition() allows preceeding transitions with zero duration to end naturally", function(test) {
+  var end0 = false,
+      end1 = false,
+      end2 = false,
+      root = jsdom.jsdom().documentElement,
+      selection = d3_selection.select(root),
+      transition0 = selection.transition().duration(0).on("end", function() { end0 = true; }),
+      transition1 = selection.transition().duration(0).on("end", function() { end1 = true; }),
+      transition2 = transition0.transition().duration(0).on("end", function() { end2 = true; });
+
+  d3_timer.timeout(function(elapsed) {
+    test.equal(end0, true);
+    test.equal(end1, true);
+    test.equal(end2, true);
+    test.end();
+  }, 50);
+});